Features of fracture surface in a fully lamellar TiAl-base alloy

The deformation mechanisms associated with different fracture surface appearances of a fatigue tested lamellar TiAl-based alloy have been studied in detail by focussed ion beam and transmission electron microscopy. The results show that linear markings within translamellar plates correspond to twins and/or slip bands. The markings in interlamellar region are associated with the crack propagation from a lamellar boundary to another. The fan-like region with linear markings belongs to a γ grain and the markings are related to twins. Intralamellar crack propagation is associated with twin–twin interaction within a γ lamella.